This invention relates generally to ambulatory medical devices and communication devices associated therewith that communicate with one another via a telemetry system and more particularly where at least portions of the data to be communicated are modified such that an increase in the number of bit transitions occur and/or the uniformity of bit transitions is improved (e.g. by randomizing the data).
Various ambulatory medical devices have been proposed and a number of such devices are commercially available. These devices include implantable infusion pumps, externally carried infusion pumps, implantable pacemakers, implantable defibrillators, implantable neural stimulators, implantable physiological sensors, externally carried physiologic sensors, and the like.
Implantable infusion pumps are generally configured to accept infusion commands from an external communication device via an RF telemetry system, or the like. These commands are, inter alia, used to set program variables that are in turn used in defining the quantity and/or timing that is used in supplying a drug to the patient. As the dispensing of appropriate amounts of the drug may be critical to the patient""s well being, it is important that a reliable communication channel exist between the external communication device and the implantable device.
Implantable devices typically operate by battery power. The batteries may or may not be rechargeable. Higher consumption of power from an implantable device containing non-rechargeable batteries leads to a shortening of the usable life of implantable device and an associated increased frequency of surgery, potential pain, recovery, and inconvenience. Higher consumption of power from an implantable device containing rechargeable batteries leads to more frequent charging periods for the batteries and associated inconvenience and may lead to an overall shortening of the usable life of the implantable device. As such, whether or not an implantable device contains rechargeable batteries or non-rechargeable batteries, it is desirable to lower the power consumption of device. As telemetry reception and transmission are highly energy consumptive, it is desirable to minimize the operation time of telemetry reception and transmission modules. As such it is desirable to ensure that message length is kept to a minimum and that repeated transmissions and attempted receptions of previously sent but unsuccessfully received messages be kept to a minimum.
As such, a need exists in the field for improved reliability of message reception. More particularly, a need exists in the art for improved information transfer efficiency by the communication system while holding the time period that the communication system is powered to a minimum. Furthermore a need exists in the art to minimize the number of communication attempts that must occur to successfully complete transfer of a message.
Some digital communication receiving systems and methods depend on the regular receipt of bit transitions in order to maintain bit synchronization between the transmitter and the receiver. This dependency is not generally a problem when messages are short but can become problematic when message length increases as the message may contain extended portions where few or no bit transitions occur. The maximum message segment length for which synchronization can be retained without bit transitions occurring depends on the type of communication system being used and the difference in clocking frequency between the transmitter and receiver.
As such, a need exists in the field for an improved way of ensuring maintenance of bit synchronization between receiver and transmitter particularly while not increasing, or at least not significantly increasing, the length of a message that is necessary to convey a given quantity of information.
A first object of certain aspects of the invention is to provide an ambulatory medical device and communication device with improved information transfer reliability.
A second object of certain aspects of the invention is to provide an ambulatory medical device and communication device with improved ability to maintain bit synchronization during reception of messages via telemetry.
A third object of certain aspects of the invention is to provide an ambulatory medical device and communication device with a telemetry system that transmits messages with an increased average number of bit transitions per bit transferred than found in the raw data to be transferred.
A fourth object of certain aspects of the invention is to provide an implantable medical device and communication device with a telemetry system that transmits messages with a more uniform average spacing of bit transitions than found in the raw data to be transferred.
A fifth object of certain aspects of the invention is to provide an ambulatory medical device and communication device with a telemetry system that transmits messages with at least a portion of the data randomized.
Other objects and advantages of certain aspects of the invention will be apparent to those of skill in the art upon review of the teachings herein. The various aspects of the invention set forth below as well as other aspects of the invention not specifically set forth below but ascertained from the teachings found herein, may address the above noted objects, or other objects ascertained from the teachings herein, individually or in various combinations. As such, it is intended that each aspect of the invention address at least one of the above noted objects or address some other object that will be apparent to one of skill in the art from a review of the teachings herein.
A first aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least some data portions of at least some messages are modified in preparation for transmission by the medical device or the communication device such that a higher number of bit transitions occur in the modified data than were found in corresponding data portions prior to preparation for transmission.
A second aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least some data portions of at least some messages are modified in preparation for transmission by the medical device or the communication device such that a more uniform spacing of bit transitions exist in the modified data than found in the corresponding data portions prior to preparation for transmission.
A third aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least some data portions of at least some messages are modified in preparation for transmission by the medical device or the communication device such that a more uniform distribution of byte patterns occur in the transmitted message than in the data portions prior to preparation for telemetry transmission.
A fourth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least some data portions of at least some messages are modified by a randomization algorithm in preparation for transmission from a first of the medical device or communication device to a second of the communication device or medical device.
A fifth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least a portion of the messages sent between the communication device and the medical device comprise a transmission preamble, an op-code for identifying the type of message being transmitted, a data portion, and an error checking code, wherein, on a predetermined basis, at least one segment of information is added to the data portion of the message prior to transmission by the medical device or the communication device and wherein the at least one segment of information comprises at least one bit.
In a specific variation of the fifth aspect of the invention, at least two bits with opposite values are added to the data portion within a prescribed number of bits of data to be transmitted.
In a specific variation of the fifth aspect of invention, the at least one segment is a plurality of segments and the plurality of segments of information are inserted at a known starting location and with fixed interval of bits between each insertion. In a further variation the inserted segments of information are one bit each. In an alternative further variation, the segments of information inserted are at least two bits each. In a further variation the at least two bits include bits of opposite value.
In an additional specific variation of the fifth aspect of the invention, the at least one segment is a plurality of segments and each of the plurality of segments of information is inserted when a predefined number of consecutive bits of data to be transmitted lack a transition and wherein at least one inserted bit has a bit value that is opposite in value to the number of consecutive bits that lacked a transition. In a further variation the inserted segments of information are one bit each. In an alternative further variation, the segments of information inserted are at least two bits each. In a further variation the at least two bits include bits of opposite value.
A sixth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least some data portions of at least some messages have a maximum separation between bit transitions reduced.
Additional specific variations, provide the medical devices of each of the above aspects and above noted variations as implantable devices such as implantable infusion pumps, implantable physiological sensors, implantable stimulators, and the like, or external devices such as subcutaneous delivery infusion pumps or sensors that ascertain a physiological parameter or parameters from subcutaneous tissue or from the skin of the patient. Such infusion pumps may dispense insulin, analgesics, neurological drugs, drugs for treating AIDS, drugs for treating chronic ailments or acute ailments. Sensors may be used to detect various physiological parameters such as hormone levels, insulin, pH, oxygen, other blood chemical constituent levels, and the like. The sensor may be of the electrochemical type, optical type, and may or may not be enzymatic in operation.
In even further variations of the above noted aspects, and above noted variations, one or more of the following is provided: (1) a first portion of the MD telemetry system is incorporated into the MD processor and a second portion of the MD telemetry system is external to the MD processor, (2) a first portion of the CD telemetry system is incorporated into the CD processor and a second portion of the CD telemetry system is external to the CD processor, (3) the MD processor includes an MD central processing unit and at least one other MD functional module, (4) the CD processor includes a CD central processing unit and at least one other CD functional module, (5) the MD electronic control circuitry includes at least one external MD functional module, other than a portion of the MD telemetry system, that is external to the MD processor, or (6) the CD electronic control circuitry includes at least one external CD functional module, other than a portion of the CD telemetry system, that is external to the CD processor.
Additional aspects of the invention set forth method counterparts to the above system aspects as well as to other functional associations and relationships, and processes that have not been specifically set forth above but will be understood by those of skill in the art from the disclosure set forth herein.
Further aspects of the invention will be understood by those of skill in the art upon reviewing the teachings herein. These other aspects of the invention may involve various combinations of the aspects presented above as well as to other configurations, that have not been specifically set forth above.